Glass composition



of the original stran Patented Aug. 3, 1954 GLASS COMPOSITION Dominick Labino, Waterville, Ohio, assignor to Glass Fibers, Inc., Waterville, Ohio, a corporation of Ohio No Drawing. Application June 15, 1951, Serial No. 231,909

7 Claims.

This invention relates to fiber glass. More particularly the invention relates to a glass composition for the manufacture of glass fibers.

Production of glass fibers attained by melting glass compositions and passing the meltedglass through small openings to obtain molten strands is known to the art. In these known processes the extruded strands are blown into long fine staple fibers which may attain a diameter as low as 30-millionths of an inch. Thus in the usual method of producing blown staple a glass strand is moved through a tubular element across the exit mouth of which a hot flame containing gases under pressure is applied. The glass strand is melted by the intense heat which may be in the neighborhood of 3000 F. and the molten material is blown transversely to the tubular element by the pressure of the gases and stretches out thereby attaining a much smaller diameter than that The blown material is then collected on a conveying element moving transversely to the direction of the blown fine staple fibers.

However in this known method the smallest fiber diameter attainable has been, as noted, 30-millionths of an inch. This limitation has been imposed by the nature of the glass composition the. characteristics of the known glass materials being such that fiber breakage occurs when an attempt is made to blow the fiber to smaller diameters. For example the surface tension of known glasses at a diameter of about 30-millionths of an inch is such that the glass is somewhat friable and breakage occurs. Interrelated with this difficulty so as to be part and parcel of the same problem is the fact that most glasses of the type usable for blown glasses melt at relatively high temperatures which leads to the lowering of the glass tensions to such an extent that the noted breakage occurs.

Accordingly a glass composition capable of satisfactorily producing strands or fibers of the order of 10-20 millionths of an inch thickness must satisfy the following particular requirements:

ing point, preferably in the range of 1800 to 1900 F. 4. The glass must have chemical attack.

a high resistivity to While some of these requirements may be fulfilled by known glasses, no glass composition *tion of these methods of oxide relatively low which fulfills all ofthe-above requirements has heretofore been'madeavailable.

Such a glass composition is desirable formany applications such as the production of very thin insulating materials in filters where a thickness of 30-millionths of an inch is unsuitable. Further it may be noted that many fiber glasses induce a sensitivity in the hands and accordingly manual operations are somewhat hindered thereby. As the diameter of the glass is reduced the elfect on the skin is less noticeable and accordingly the attainment of lower diameters isdesirable from this point of view.

It is a primary object of this invention to provide a glass composition which meets all of the requirements set forth above.

It is an important object of the present invention to provide a glass composition which permits of the production of glass fibers or strands having a diameter in the range of 10 to 20-millionths of an inch.

I have found that these and other objects of the invention may be accomplished by incorporating into a glass composition approximately 10% by weight of metallic oxide selected from the group .of copper and lead oxides and maintaining the weight ratio of the magnesium and calcium oxide in the composition to the selected in order to secure the required low softening point. Further the content of the selected oxide may vary between about 9 to 10.5 percent of the weight of the glass, but the sum total of the selected oxide, the magnesium and calcium oxides should always be substantally constant, that is, if the selected oxide weight is lowered the magnesium or calcium oxide or the total of both should beincreased to the'same extent. The glass composition may be formed by any of the usual methods known to the art and accordingly no descripformulation will be given herein.

The invention may be explained more fully by reference to the following examples ofglass compositions which are particularly suitable for the practice of the invention.

Example I Constituent: Percent by weight SiOa 54.3 CaO 6.92 MgO 4.12 NazO .36 B203 10.5

A1203 TiO2 13.98 F8203 CuO 9.82

Total The component containing the A1203 plus T102 plus F0203, set forth in the above examples, generally comprises a small amount of F8203 and T102, the prime portion being A1203. A typical breakdonw of this component shows in parts by weight:

A1203 .1 55.52 T102 .54 FezOa .43

Example III A commercial batch may be. produced by using the following components in parts by weight:

Sand 194.8

Burnt nme 30 of an oxide selected from the group of copper Clay 695 and lead oxides, the balance being essentially Boric acid 892 aluminum oxide.

Aluminum hydrate 421) 2. A fine glass fiber having substantially the Fluorspar following composition by weight:

Salt cake .1 3.2 Percent CuO 40.0 9*

A typical chemical analysis of the above com- MgO 4.1

ponents follows: 1 B209 10.5

s10 OaO MgO NagO Bio. FezOa To. A110; K10 CuO It will be noted that in each of the foregoing examples that the total of the selected oxide and the magnesium and calcium oxides is approximately 20 percent by weight of the glass. Further in each instance the ratio of the sum of the calcium and magnesium weights to that of the selected oxide is very close to 1:1. Under these conditions the softening points of the glass are low for this type of material, that is about 1800 to 1900 degrees Fahrenheit. Further the glasses when molten will have the low surface tension and high interfacial tension required for the production of fibers in the range of 10 to 20- millionths of an inch diameter.

It will be understood that this invention is susceptible to modification in order to adopt it to difierent usages and conditions and accordingly it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

l. A fine glass fiber having substantially the following composition by weight:

Percent S102 54.3-54.7 5 08.0 6.35-7.43 MgO 3.98-4.12 B203 10.2-10.5

more than 9 percent and Clay v Boric Acid Aluminum Hydrate- Flourspar Salt Cake..-" Cu0 The moisture content of the various constituents is not specifically set forth above'but may be derived from the component weight and the summation of the constituent oxides izreaeh case.

- Example IV. S102 V 54.33 CaO 7.43 MgO 4053' N320 .37 B203 10.2

A1203 T102 14.60 FezOs CuO. 9.02 100.00

Example V S102 .Q. 54.75 02.0 6.35 MgO 3.98 NazO 35 B203 10.4 A1203 T102, 13.75 F8203 PbO 10.42

and more than 9 percent and less than 10.5 percent of an oxide selected from the group of copper and lead oxides, the balance consisting esoxide. having substantially the sentially of aluminum 3.'A fine glass fiber 1 following composition, by weight:

Constituent: Percent by weight S102 5 30 0:10 6.92 MgO 4.12 NazO 0.36 B20: 10.50 RzOs-t-TiOz 13.98 CuO 9.82

4. A fine glass fiber having substantially the following composition, by weight:

5. A fine glass fiber having substantially the batch has substantially the following composifollowing composition, by weight: tion:

Constituent: Percent by weight Constituent: Parts by weight: SiOz 54.33 Sand 194.8 CaO 7.43 5 Burnt lime 37.6 MgO 4.05 Clay 69.6 Na2O 0.37 Boric acid 89.2 B203 10.20 Aluminum hydrate 42.0 R2 O3+Ti0z 14.60 Fluorspar 6.0 CuO 9.02 Salt cake 3.2

6. A fine glass fiber having substantially the Cuo fOllOWlIlg composition, by welghtz References Cited in the file of this patent g g Percent by gff g H UNITED STATES PATENTS Ca; :iiiijiiiiliiiiiii"iii T 6'35 Number Name Date Mgo 1,529,259 Locke et a1 Mar. 10, 1925 Nazo I 2,100,391 Grimm et a1. Nov. 30, 1937 B203 10") 2,394,493 Schoenlaub Feb. 5, 1946 R2O3+Ti0z :QIIIIIIIZ 13:75 20 2517459 Armistead 1950 PhD 10.42

'7 A fine glass fiber made from a batch, which 

1. A FINE GLASS FIBER HAVING SUBSTANTIALLY THE FOLLOWING COMPOSITION BY WEIGHT. MORE THAN 9 PERCENT AND LESS THAN 10.5 PERCENT OF AN OXIDE SELECTED FROM THE GROUP OF COPPER AND LEAD OXIDES, THE BALANCE BEING ESSENTIALLY ALUMINUM OXIDE. 